Description: The large, disc-shaped thalli of this blue-grey lichen are found mostly on basic barked trees in the west in well-established, well-lit woodland, scrub or swamp. It may also occur in sheltered cliff sites close to the sea. Like its relative D. plumbea it is a robust plant with a lobed, fan-shaped margin and felt-like underside, but unlike that species it is only very occasionally fertile. It differs more profoundly in that the surface is covered with globose isidia the same colour as the thallus. It is not infrequent in Ireland.

Key Identification Features:

• The thick, pliable thallus, fan-like symmetry and surface covered with globose isidia strongly suggest this species
• It is separated from the otherwise similar bur rarer Degelia ligulata by the peg-like or globose isidia. In D. ligulata the isidia are more flattened or spatula-shaped.

Original text submitted by Simon Davey

Distribution Map from NBN: Pectenia atlantica at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Pectenia atlantica at iNaturalist World Species Observations database.